The present invention relates generally to fluid flow valves, and more particularly to a check valve with reduced or controlled opening speed.
Check valves are one-way valves used in a variety of applications to facilitate mono-directional fluid flow. When pressure differential across a check valve in the flow direction exceeds a cracking pressure, the valve opens. Check valves can take a variety of forms, including diaphragm, ball, duckbill, and swing valves. Some check valves have apertures covered, in a closed state, by hinged flappers that can only open in one direction (i.e. in a fluid flow direction). Such check valves typically include stop pins that halt opening of the flappers at a predetermined maximum angle. When differential pressure across the check valve drops sufficiently, or changes directions, the check valve closes.
The flappers of flapper-based check valves can be damaged by repeated impact against stop pins. This damage can, for instance, take the form of cracking or deformation, and reduces part lifetimes.